Eosinophil Methods

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From:"Histomail\\" <histomail@netspace.net.au> (by way of Marvin Hanna)
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Recently the issue of
determining eosinophils in sections arose. this was part of a debate on
whether some lesions were caused by parasitic action or some other cause.
The stain i found was Luna's Stain originally in 'AFIP manual of Histologic
Staining Methods' and later in 'Theroy and Practice of Histotechnology" by
Sheehan and Hrapchak. I've done a number of sections and the eosinophils
stain quite well. The issue is convincing one of the pathologists how
reliable the stain is. Is there any references or experience in the use of
this stain or any other stains for eosinophils?

There are a plethora of methods suitable at demonstrating Eosinophils. The
majority of these relying upon Eosin brightly staining the cytoplasmic
granules, even the humble H&E does this quite well if you use a Buffered
Eosin with a pH of 5.3-5.5. Other methods include any of the Romanowsky
stains or even just buffered eosin on its own as used to incoporated in
Dunger's Fluid used in early Haematology.
Be warned the appearance of Eosinophils in paraffin sections is quite
different to that seen in smears; sections tending to have granules
overlying each other such that often the cytoplasm appears bright red
without any granule definition along with condensed chromatin in the
nucleus, depending upon section thickness, whereas smears almost always tend
to produce discrete granules and good chromatin definition and nuclear
As to specific identification and convincing the enquiring Pathologist, that
at least in the application to blood and bone marrow smears, the peroxidase
reaction with and without Cyanide is highly specific, with eosinophils being
the only cell line to still be positve with cyanide treatment; paralell
testing without cyanide serves as an inbuilt positive control as all
granulocytes should be positive. This may have application to sections, but
I don't have access to a Pearse.( Suggested Ref ex. LIllie 4th Ed. pp750.
ref.Am.J.Clin.Path.55:283,1971.) Visualisation would of course depend upon
what other structures might be positive in sections, and maybe paraffin is
unsuitable anyhow, and frozen sections only can be used.
Perhaps someone else out there would like to comment?
Mike Rentsch.

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